Japanese Patent Disclosure No. 53-59728 discloses a heat-expansible covering composition produced by dispersing 5 weight percent to 50 weight percent, or, more preferably, 10 weight percent to 30 weight percent, heat-expansible microspheres in a crosslinking type synthetic resin emulsion. The crosslinking type synthetic resin emulsion is a an epoxy emulsion, a urethane emulsion, self-crosslinking type acrylic emulsion or a reaction type acrylic emulsion that may be crosslinked using a crosslinking agent. The covering is printed or coated onto a substrate and heated to expand and crosslink the coating and thereby form an ornamental material having an irregularly patterned layer on the surface of the substrate.